The effect of oral administration of a preparation of human urine (PHU) on the progression of acute liver injury was examined in rats intoxicated with carbon tetrachloride (CCl4) and alpha-naphthylisothiocyanate (ANIT) PHU protected the liver from CCl4-induced injury as judged by morphological and biochemical observations. In contrast, PHU aggravated ANIT-induced injury as judged also by morphological and biochemical observation. PHU prevented the increase in hepatic glutathione (GSH) and lipid peroxidation induced by CCl4. But PHU enhanced the increase in hepatic GSH caused by ANIT. These results indicate that the effect of PHU on hepatic GSH concentrations is through an indirect pathway. Clinical application of PHU on hepatitis should be explored further.